1.Nominal Ball Diameter, Dw:

The designated diameter value used to represent the size of a ball.

2.Single Ball Diameter, Dws:

The distance between two parallel planes tangent to the actual surface of the ball.

3.Mean Ball Diameter, Dwm:

The arithmetic mean of the ball's maximum and minimum single diameters.

4.Ball Diameter Variation, Vdws:

The difference between the maximum and minimum single diameters of the ball.

5.Sphericity Error, Tdw:

The maximum radial distance between the smallest circumscribed sphere and the largest inscribed sphere, both concentric to the least-squares sphere within any equatorial plane.

6. Ball Lot:

A specific quantity of balls manufactured under identical conditions and treated as a single unit.

7.Ball Lot Mean Diameter, Dwml:

The arithmetic mean of the average diameters of the largest and smallest balls within a lot.

8.Lot Diameter Variation, Vdwl:

The difference between the average diameters of the largest and smallest balls within a lot. This definition applies exclusively to balls graded G3 through G200.

9.Ball Gauge Tolerance, St:

The permissible range of lot mean diameter for a specific ball gauge.

10.Gauge Interval, Ig:

The incremental change in nominal ball diameter between successive gauges.

11.Ball Grade, G:

A specific combination of tolerances for size, shape, surface roughness, and sorting accuracy.

12.Ball Gauge Value, S:

The deviation between the lot mean diameter and the nominal ball diameter, corresponding to a predefined series value.

13.Ball Lot Gauge Deviation, ΔS:

The sum of the lot mean diameter minus the nominal ball diameter and the ball gauge value:

ΔS=Dwml−(DwS).

14.Hardness:

A measure of a ball’s resistance to localized deformation, determined using a specific testing method.